1. Field of the Invention
The present invention relates to an oral solid preparation and a method of manufacturing the same, and more specifically to an oral solid preparation that is stable to light and a method of manufacturing the same.
2. Description of the Related Art
Some of base compounds having drug effects are extremely unstable to light. For example, amlodipine, which is a dihydropyridine calcium antagonist, has a long half-life in blood and is widely used in the clinical field as an antihypertensive drug for once-a-day ingestion.
However, in general, dihydropyridine drugs have problems of light stability. Among the drugs, amlodipine is a compound that is relatively hard to decompose by light, but in the case where amount of the exposed light is much, the compound is decomposed, resulting in lowering of its medicinal properties.
Accordingly, formulation of amlodipine requires a technique for ensuring light stability.
For example, there is suggested a tablet having light stability improved by coating a tablet of a dihydropyridine derivative with a film agent containing ferric oxide (for example, JP 2003-104888 A).
However, in the case of a preparation that is required to degrade within 30 seconds in the oral cavity like an oral disintegrating tablet, only such a technique to coat the whole tablet may impair rapid degradability, resulting in insufficient exertion of its functions. It is technically possible to produce particles by coating the whole of a drug, but the coating may impair the ability of the drug to be rapidly eluted from the particle and prevent sufficient exertion of the drug effects after an administration of the drug.
Moreover, there is suggested a method of enhancing the light stability of an uncoated dihydropyridine drug. Examples of the method include a method that includes adding yellow ferric oxide to nifedipine to suppress the production amount of an oxidant produced by light and to prevent a reduction in the base component content (JP 55-22645 A).
However, this document has no description about amlodipine.
On the other hand, another document introduces the fact that blending of ferric oxide can prevent discoloration or decomposition of amlodipine and a pharmaceutically acceptable salt by light (JP 2006-306754 A).
However, this document describes only prevention of discoloration or decomposition caused by yellow ferric oxide and does not describe a sufficient study on the effects of other colorants.